1. Field of the Invention
The present invention relates to a circuit module, and more specifically, relates to a circuit module in which a plurality of non-reciprocal circuit elements are provided.
2. Description of the Related Art
As an existing non-reciprocal circuit element, for example, a non-reciprocal circuit element described in Japanese Unexamined Patent Application Publication No. 2006-311455 is known. The non-reciprocal circuit element includes a ferrite having a pair of opposing principal surfaces, a plurality of center electrodes, permanent magnets having principal surfaces facing the principal surfaces of the ferrite, and a circuit board. The plurality of center electrodes are formed from a conductor film in a state of being insulated from the principal surfaces of the permanent magnets and intersecting each other, and are electrically connected via intermediate electrodes formed on end surfaces orthogonal to the principal surfaces of the ferrite. Furthermore, the ferrite and the permanent magnets are disposed on the circuit board such that the principal surfaces thereof are orthogonal to the surface of the circuit board. The non-reciprocal circuit element described above is used, for example, in a communication apparatus or the like.
Meanwhile, in recent years, with demand for size reduction of communication apparatuses, size reduction of non-reciprocal circuit elements have been increasingly demanded. Thus, it is proposed to remove a yoke for suppressing leakage of magnetic flux to the outside, in the non-reciprocal circuit element described in Japanese Unexamined Patent Application Publication No. 2006-311455.
However, when the yoke is removed from the non-reciprocal circuit element, magnetic flux leaks around the non-reciprocal circuit element. Since a communication apparatus is provided with a plurality of non-reciprocal circuit elements, if leakage of magnetic flux occurs, the non-reciprocal circuit elements are magnetically coupled to each other. As a result, the characteristics of the non-reciprocal circuit elements vary.